Fill big bins with soapy water and add large sponges.
The children love dunking the sponges in and carrying them to the vehicle of their choice to scrub.
Then have buckets for rinsing the cars.
We used a small sprinkler and smaller buckets for rinsing. The children got cooled off in the sprinkler while waiting for their rinse buckets to fill. They can even ride through the rinsing station on the soapy bike or car.
It’s even more fun if you play some cool music outside as well!
And the added bonus is that all of your bikes, trikes and cars will be nice and clean.